Chemical mechanical polishing (CMP) is generally known in the art. For example U.S. Pat. No. 5,177,908 to Tuttle issued in 1993 describes a finishing element for semiconductor wafers, having a face shaped to provide a constant, or nearly constant, surface contact rate to a workpiece such as a semiconductor wafer in order to effect improved planarity of the workpiece. U.S. Pat. No. 5,234,867 to Schultz et. al. issued in 1993 describes an apparatus for planarizing semiconductor wafers which in a preferred form includes a rotatable platen for polishing a surface of the semiconductor wafer and a motor for rotating the platen and a non-circular pad is mounted atop the platen to engage and polish the surface of the semiconductor wafer. Fixed abrasive finishing elements are known for polishing semiconductor layers. An example is WO 98/18159 PCT application by Minnesota Mining and Manufacturing.
An objective of polishing of semiconductor layers is to make the semiconductor layers as nearly perfect as possible. Fixed abrasive finishing pad finishing surfaces can suffer from being overly harsh on a workpiece causing unwanted scratching or other unwanted surface damage thus reducing the perfection of the surface. Further, a fixed abrasive finishing pad finishing surface can suffer from having a higher than necessary friction when finishing a workpiece. This higher than necessary friction can lead to other unwanted surface damage. Further, fixed abrasive finishing pads can have abrasive particles unexpectedly break away from their surface during finishing and these broken away abrasive particles can scratch or damage the workpiece surface. Still further, during finishing a particle can break away from the workpiece surface forming a workpiece abrasive particle which can scratch or damage the workpiece surface. These unwanted effects are particularly important and deleterious to yield when manufacturing electronic wafers which require extremely close tolerances in required planarity and feature sizes.
It is an advantage of this invention to reduce the harshness of fixed abrasive finishing pads on the workpiece surface being finished. It is an advantage of this invention to reduce unwanted scratching or other unwanted surface damage on the workpiece surface during finishing. It is further an advantage of this invention to reduce the friction during finishing to help reduce unwanted surface damage. It is an advantage of this invention to reduce unwanted damage to the workpiece surface when during finishing with a fixed abrasive finishing element an abrasive particle unexpectedly breaks away from their surface. It is an advantage of the invention to reduce unwanted damage to the workpiece surface when an abrasive workpiece particle breaks away workpiece surface during finishing. It is further an advantage of this invention to help improve yield for workpieces having extremely close tolerances such as semiconductor wafers.
These and other advantages of the invention will become readily apparent to those of ordinary skill in the art after reading the following disclosure of the invention.
A preferred embodiment of this invention is directed to a method of finishing of a semiconductor wafer surface being finished comprising the step a) of providing a finishing element finishing surface having an organic lubricant; the step b) of positioning the semiconductor wafer surface being finished proximate to the finishing surface; the step c) of applying an operative finishing motion in the interface between the semiconductor wafer surface being finished and finishing element finishing surface; and wherein applying the operative finishing motion transfers the organic lubricant from the finishing surface to the operative finishing interface in a manner that forms a organic lubricating film of from 1 to 6 molecules thick which adheres to the semiconductor wafer surface being finished.
A preferred embodiment of this invention is directed to a method of finishing of a semiconductor wafer surface being finished comprising the step a) of providing a finishing element finishing surface capable of abrading the semiconductor wafer surface during finishing; the step b) of positioning the semiconductor wafer surface being finished proximate to the finishing surface; the step c) of providing an organic lubricant proximate to the surface of the semiconductor wafer surface being finished; the step d) of applying an operative finishing motion in the operative finishing interface comprising the interface between the semiconductor wafer surface being finished and the finishing element finishing surface; and wherein applying the operative finishing motion forms an organic lubricating film layer of at most 10 molecules thick which interacts with and adheres to the semiconductor wafer surface being finished.
A preferred embodiment of this invention is directed to a method of finishing of a semiconductor wafer surface having unwanted raised regions being finished comprising the step a) of providing an abrasive finishing surface; the step b) of positioning the semiconductor wafer surface being finished proximate to the finishing surface; the step c) of providing an organic lubricant between the abrasive finishing element finishing surface and the conductive region of the semiconductor wafer surface being finished; the step d) of applying the operative finishing motion that transfers the organic boundary lubricant from the finishing surface to an operative finishing interface comprising the interface between the abrasive finishing surface and the semiconductor wafer surface being finished forming an organic lubricating film in the operative finishing interface; and the step e) of controlling the thickness of the organic lubricating film by changing at least one control parameter in a manner that changes the tangential force of friction in at least two different regions of the operative finishing interface in response to an in situ control signal.
Other preferred embodiments of my invention are described herein.